The present invention generally relates to systems and methods for treating water and more specifically relates to systems and methods for separating debris and contaminants from water passing into drains, for example storm drains adjacent paved surfaces, such as along streets in municipalities, parking areas and other similar locations.
Drainage systems collect and direct rainwater and runoff to underground storm sewers to prevent flooding of streets. In some geographic regions, this untreated water is drained directly into the ocean not far from public beaches. Until relatively recently, it was not well appreciated that even residential runoff water can be highly contaminated, and may pose serious threats to the environment and public health.
Typical storm drainage systems include drain inlets placed at margins of streets and roadways and adjacent sidewalks. The drain inlet is commonly equipped with a removable iron grate element that covers at least a portion of the inlet. In addition to providing a safety means, for example to prevent small children and animals from falling into the drain opening, the grate element is designed to prevent some of the relatively larger debris and trash items, such as tree branches, large paper or plastic containers, from entering the storm drain inlet. However, substantial volumes of relatively smaller trash items and debris, including lawn clippings, leaves, empty beverage containers, paper and plastic wrappers and the like, regularly pass into storm drains despite the use of iron grates. These items will eventually cause clogging of the drainage system if not periodically removed. In addition, such iron grates have been found to be ineffective in preventing gradual accumulation of solid materials that enter the drain inlet through open spaces between edges of the drain inlet and a perimeter of the grate element.
Assemblies have been developed for filtering a water flow entering drain system inlets. For example, it is known to place a screen or other porous element below the grate element to collect smaller trash and debris. However, such systems are prone to becoming clogged with debris, thereby obstructing water flow into the storm drain. In addition, such assemblies have not been designed for screening relatively low water flows into the drain inlet. A particularly slow water flow will often bypass the assembly entirely by seeping through unfiltered areas between edges of the assembly and the drain inlet.
Moreover, such periods of low water flow, especially following a relatively long xe2x80x9cdry spellxe2x80x9d tend to bring highly contaminated runoff water into the drains. This is due to long term accumulation of oils, automobile fluids, dust, dirt, lawn pesticides and other contaminants in the gutter areas of residential and industrial streets.
Devices have been proposed to address the problem of polluted runoff water in drainage systems. For example, U.S. Pat. No. 6,106,707 to Morris et al., which is incorporated herein in its entirety by this specific reference, discloses a modular insert for curb-inlet storm drains for collecting both trash and oil and other hydrocarbons. The device generally comprises a perforated hopper that fits inside a storm drain inlet. The hopper contains fragments of oil absorbent material for entrapping oil in runoff water flowing through the hopper. Although addressing some of the problems associated with present drainage systems, the Morris et al. device and similar conventional devices may be inconvenient and expensive to maintain and do not address other problems that are solved by the present invention.
New drainage filter apparatus and systems for debris and contaminant removal have been discovered. Such apparatus and systems are straightforward in construction and highly effective in removing particulate matter, debris and contaminants, such as hydrocarbons and other harmful substances from water flowing through a storm drain. The present systems are also easy and inexpensive to maintain and do not hinder or obstruct water flow into drainage systems.
Generally, the present invention is directed to an apparatus for removing debris and contaminants from water passing through a storm drain, for example a storm drain along a city street. The present apparatus typically comprises a debris trap adapted to fit within the storm drain, wherein the debris trap includes a porous element adapted to separate debris from a water flow passing through the storm drain. The apparatus further comprises a frame having a peripheral portion adapted to direct the water flow into the porous element of the debris trap and to prevent bypass of the debris trap during low water flow conditions.
Preferably, the peripheral portion of the frame is sized and shaped to substantially overlap an edge of an inlet opening of the storm drain. In a specific embodiment of the invention, the peripheral portion of the frame comprises an angled iron frame element.
Advantageously, the porous element comprises a sieve element that is removably connected to the frame to facilitate periodic removal and cleaning and/or replacement thereof. The porous element preferably further comprises at least one handle member adapted to facilitate the manual removal of the sieve element from the frame.
The apparatus preferably further comprises a body portion depending from the frame and extending beneath the porous sieve element. The body portion is made of a substantially non-water permeable material, for example a nylon or other polymeric material, and importantly includes an outlet for allowing the water flow to pass into the drain outlet into the sewer system. Furthermore, the body portion and outlet are advantageously structured so that substantially all water passing into the body portion is passed through the outlet before being discharged from the storm drain. A filter member, for example a filtering screen, may be secured across the body portion outlet.
Preferably, the apparatus further comprises a contaminant containment element secured, preferably removably secured, across the body portion outlet. The contaminant containment element comprises a contaminant removal material effective to remove one or more selected contaminants from the water flow as the water flow passes through the contaminant containment element and finally into the storm drain outlet. For example, the contaminant removal material may comprise a material that physically or chemically interacts with contaminants in water, for example dissolved in water, to prevent such contaminants from passing the contaminant containment element and into the sewer system. In one embodiment, the contaminant removal material comprises an oil absorbent material such as polypropylene, though other materials may also be useful depending upon the selected contaminants to be removed, for example, materials which are effective to remove components, microbes, soluble waste products, other water soluble contaminants and the like may be included in the contaminant containment element. Many such materials are known and commercially available. The filtering screen is preferably secured across the body portion outlet downstream of the contaminant containment element.
In one particularly advantageous embodiment of the invention, the porous sieve element comprises a material having a flow rate capacity of at least about 145 gallons per minute per square foot. For example, the material may be a material having a 40 Sieve (U.S. Sieve) porosity. It is further noted that the filtering screen secured across the outlet may comprise the same or similar material.
The present invention is designed to facilitate removal and replacement of the contaminant containment element. After a period of use, the containment element may require replacement in order to assure quality of filtering thereby. For example, the contaminant containment element may be contained by a flexible pocket element defined by the body portion. More specifically, the pocket element is located at least partially about the body portion outlet, preferably substantially surrounding the body portion outlet. The pocket element is structured to at least assist in securing the contaminant containment element across the body portion outlet. The pocket is designed to prevent the contaminant containment element from shifting or otherwise becoming displaced from its desired position across the outlet. In one embodiment, the contaminant containment element is a xe2x80x9cpillowxe2x80x9d form, which further facilitates removal as needed. The contaminant removal material may be encased in a porous mesh or woven material for example in the form of a pillow or other conveniently removable configuration.
One aspect of the present invention is directed to a system for removing debris from water passing into a storm drain having both a back curb inlet opening and a gutter inlet opening. More specifically, the system of this aspect of the present invention comprises the debris trap assembly described elsewhere herein, and in addition a debris block assembly that is structured and sized to be positioned across the back curb inlet opening.
Particularly, the debris block assembly is designed to direct water and debris into the gutter inlet opening to prevent bypass of the present debris trap. The debris block assembly preferably comprises an outer sleeve, an inner sleeve disposed within the outer sleeve, and means, for example one or more sealing members, for sealing or securing the debris block assembly against edges of the back curb inlet opening of the storm drain. The means for sealing or securing may include for example, flexible foam end members disposed in opposing ends of the inner sleeve. The outer sleeve preferably comprises a textile material or other suitable material, such as a geotextile material, to be described in greater detail hereinafter. The inner sleeve preferably comprises a polymeric, e.g. PVC or the like, pipe or member which is substantially rigid and is effective for providing rigidity to the assembly. A relatively heavy metal, e.g. iron, steel or the like, bar having a length longer than the length of the inlet opening may also be provided to secure the debris block assembly in place.
Each individual feature and each combination of two or more features described herein are included within the scope of the present invention provided that the features included in the combination are not mutually inconsistent.
These and other aspects and advantages of the present invention are set forth in the following detailed description and claims, particularly when considered in conjunction with the accompanying drawings in which like parts bear like reference numerals.